<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <select v-model="selected">
      <!-- 如果设置了 value 值，则选择当前option的时候，使用 value 值赋值。 -->
      <option value="">请选择</option>
      <option value="tianjID">天津</option>
      <option>B</option>
      <option>C</option>
    </select>
    <span>Selected: {{ selected }}</span>
  </div>

  <script src="./js/vue.js"></script>
  <script>
    
    const app = new Vue({
      el: '#app',
      data: {
        selected: 'A'
      },
    })
  </script>
</body>
</html>